Fertilisers for Ornamentals

The latest products are helping to simplify the complexities of plant nutrition, according to Sally Drury.

Osmocote Bloom (left) gave uniform growth and optimum colour in tests - image: Scotts Professional
Osmocote Bloom (left) gave uniform growth and optimum colour in tests - image: Scotts Professional

Plants need nutrition, but what type? How and when should you apply them for best results and cost-effectiveness? Nutrition can be complex. Fortunately, fertiliser manufacturers are developing new products, even new technologies, to help simplify feeding programmes.

A common way of providing nutrition to bedding plants is by applying soluble fertilisers through the irrigation system. For the grower, it means balancing nutritional requirements with the need for water and leaching effects. Then there is the question of nutrient supply to the plant when it reaches the garden centre and sits on display. Scotts Professional believes it has the answer.

Osmocote Bloom is a controlled-release fertiliser (CRF) specifically designed for annuals in small pots - simplifying production and delivering quality, cost and environmental benefits. With an NPK of 12-7-18, plus 1.5MgO and all the essential trace elements, it is tailored to the exacting needs of bedding plants. It supplies NPK in a ratio of 2:1:3 for condensed growth.

The mini-granules can be incorporated in any pre-mix growing media, while the two-to-three month longevity given by the resin-coating technology eliminates the need for water-soluble fertilisers and ensures the plant is fed throughout production as well as in the retail phase.

"Simplifying production, Osmocote Bloom supplies the total nutrient needs for the whole crop cycle," says Scotts Professional marketing manager Dave Steward. "It helps shorten the cycle and delivers improved shelf life for the retail trade and consumer.

"Osmocote Bloom can significantly cut total fertiliser usage and cost. With margins squeezed, growers must scrutinise all production costs to find savings, while retaining quality. Osmocote Bloom can help growers reduce total fertiliser usage by 55 per cent and cost by more than 30 per cent. This does not take into account additional savings from shortening the production cycle and reducing total labour costs."

Scotts Professional technical manager for fertilisers Andrew Wilson points out the environmental benefits. "You use fewer kilos of fertiliser, less water and getting compact growth without using a lot of regulator. It is the way forward," he says.

The effects of Osmocote Bloom on plant quality and nutrient leaching were tested at the official trial station RATHO, Brindas in France, using the product on a range of bedding plants and comparing to organic and water-soluble fertilisers. Key conclusions included that Osmocote Bloom gave the best quality in all varieties tested in terms of uniform growth and optimum colour.

It also showed lower N leaching than when plants were fed soluble fertilisers and gave the lowest phosphate leaching.

Recommended application rates range from light feeding at 1.5-2g/l to 3-4.5g/l as a heavy feed. The product is supplied in 25kg packs.

Bridging the gap between rooting and repotting, Scotts Professional's second new product has been specifically developed for applications in small substrate volumes. Osmocote Exact Mini (15-9-11-2MgO+TE) is intended for pots smaller than 8cm in diameter, including plugs and trays with small compartments. The granules are six times smaller than standard Osmocote Exact granules, enabling good distribution even in volumes starting at 20ml.

Osmocote Exact Mini can be applied by mixing it into the growing medium or by top dressing once the roots are developed. It is supplied in buckets, 10kg in weight, and comes in two formulations with longevities of either three-to-four or five-to-six months. Both contain a complete package of trace elements and magnesium.

Magnesium is important, particularly for quality in ornamental crops, so growers often apply extra during the season. A trace-element package containing extra magnesium, as well as iron, is now offered by Scotts Professional. Micromax Premium can be pre-mixed into substrates for containerised ornamental nursery stock and pot plants, but can also be used in field applications. Wilson suggests it is also beneficial where irrigation water is soft, having been harvested from roofs.

In trails, the controlled-release Micromax Premium showed good effect on iron-demanding crops such as buxus, calluna, cytisus, hebe, hydrangea, pieris and vinca. It is also recommended for crops where only the highest quality will do.

Miromax Premium contains 15 per cent MgO, 25 per cent of which is delivered direct while 75 per cent is slowly available over 16-18 months. It stimulates rooting and strong and healthy crops with good plant colour. Application rates range from 0.1g/l for cuttings in peat-based substrates to 1g/l for container nursery stock growing in bark-based substrates.

Top dressing container trees and shrubs is popular and now growers have more choice of product. New from Vitax Grower comes Q4 Top, a double-duty, granular fertiliser specifically designed for top dressing container-grown nursery stock.

With a rapid early release of nutrients followed by a sustained release lasting three months, the 11-5-12+ 1Mg + trace elements formulation contains plant extracted product. Applied now, Q4 Top will aid recovery of medium and larger container-grown species promoting optimum plant health well into midsummer.

Extending Scotts' popular coated top dress range for container ornamentals, OsmoTop is recommended for quick greening up or correction of deficiency symptoms in well-rooted ornamental nursery stock.

OsmoTop is an economy version of Osmocote Topdress NT and has a shorter longevity of two-to-three months as well as providing a fast start portion of nitrogen. The analysis of 23-5-10-2MgO+TE contains 40 per cent coated nitrogen and 60 per cent uncoated for quick green-up.

"The 12-month CRF given to plants potted last April or May will have seen them through until now," says Wilson. "But it is now, just as they come into spring, that plants are at their largest and have a big demand for nutrient. OsmoTop can green them up and enhance the glossiness and saleability."

Like Topdress NT, OsmoTop will stick to the growing media surface, with no loss of granules in the event of the pots being blown over.

To help growers plan their growing season, Scotts Professional has introduced an integrated growing package called iGro. As part of the programme, growers get exclusive offers on plant protection, soluble fertiliser and Osmocote CRF products.


A problem often associated with urea nitrogen fertiliser is the loss of ammonia from volatilisation and nitrous oxide from denitrification - and substantial nitrogen loss is bad for your crop, your pocket and the environment. A new fertiliser, KaN (Koch Advanced Nitrogen), minimises volatilisation by incorporating Agrotain technology based on a urease inhibitor.

KaN utilises the technology to achieve a performance that is comparable to ammonium nitrate fertiliser. It does this primarily by minimising volatilisation - conversion of urea to ammonia gas - which takes place on the soil surface after urea fertiliser has been applied.

The product delivers the low volatilisation and high agronomic performance expected with more expensive ammonium nitrate fertilisers. However, since KaN is manufactured using urea, it provides advantages in cost, reliable supply and simplified transport and storage. It is available as a straight nitrogen granular-grade product but can also be used as a component of NPK fertiliser blends.

"Growers and distributors are struggling more than ever with rising nitrogen prices, sporadic availability and the burden of handling ammonium nitrate. Innovation and choice, backed by a reliable supply level, is part of Koch Fertilisers' commitment," says a company representative.

The effectiveness of Agrotain has been demonstrated by UK research such as the ADAS-led Defra NT26 project and by Cambridge Arable Technologies' trials at Haverhill in Suffolk.

KaN is produced by Koch Fertilisers, which opened UK offices in Marlborough, Wiltshire, at the beginning of 2010. The company is a subsidiary of US-based Koch Fertilizer LLC, which manufactures and distributes nitrogen fertiliser across global markets. KaN is produced at Koch's new deep-water facility in Avonmouth, Bristol, which saw its first vessel arrive with 22,000 tonnes of urea nitrogen at the end of last year.


A concentrated form of zinc ammonium acetate, Hortifeeds's Generate stimulates increased chlorophyll, speeding up photosynthesis and enhancing carbohydrate production.

It is available with new wetters and stickers to ensure maximum penetration and a source of iron chelate has also been introduced.

A substrate designed to improve water and air holding capacity of any compost, Fytocell was recently added to the Hortifeed range of products. Supplied to landscapers, Fytocell is now available to commercial growers in slab form and also as flakes that can be added at 20 per cent by volume to increase pore space in potting mixes.

Amenity Land Solutions 01952 641949
Charles Morris 01784 481184
Compo Professional 01299 879923
Fargro 01903 721591
Fertil UK 01948 770008
Haifa Chemicals 00 32 152 70811
Green-Tech 01423 332100
Hortifeeds 01522 704404
Koch 01672 518290
Maxicrop 08700 115117
Rigby Tyalor 01204 677777
Scotts Professional 01473 201100
Sinclair Horticulture 01522 537561
Solufeed 01243 554090
Vitax Hortifieeds 01530 510060
Yara UK 01469 554648

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